In a technical field of fabricating display panels, as the rapid development and constant improvement of TFT-LCD (thin film transistor liquid crystal display) technology, the size of a liquid crystal display panel increases constantly as well. The size of a display substrate such as a color filter substrate, as an important component in a liquid crystal display panel, increases accordingly. Therefore, main manufacturers of display panels need to establish a manufacturing line of a new generation, so as to produce color filter substrates with larger sizes. However, doing in this way involves high investment and high risk. Therefore, manufacturing a color filter substrate with a larger size by a current manufacturing line is becoming a research focus.
In a fabrication process of a color filter substrate, a plurality of exposures is conducted. Firstly, in order to make an opening portion of the color filter substrate, a black film layer is coated on a transparent substrate and an exposure is then performed, so as to form a black matrix structure; and then, film layers such as a blue film layer, a green film layer and a red film layer are coated in sequence, which are then exposed and developed to form blue pixels, green pixels and red pixels. And then, after a common electrode is formed on the black matrix structure, the blue pixels, the green pixels and the red pixels, a spacer material layer is coated as well, which is then exposed and developed to form post spacers. The exposure process employed to form the black matrix structure is called a primary exposure, and the exposure process employed to form pixel resin and post spacers is called a secondary exposure. In practice, in order to ensure accurateness of the plurality of exposures, a method as below is commonly employed: an alignment mark is formed respectively at edges of two opposite sides of the transparent substrate after the primary exposure process; and in the secondary exposure process, two mark holes at edges of two sides of a mask are aligned with the alignment marks at the transparent substrate, so as to make positions of the secondary exposure accurate, so that patterns on the mask can be precisely transferred to corresponding positions of the transparent substrate, and pixels as well as post spacers that are accurately arranged can be obtained.